Output regulated pump



July 9, 196s K. Ecm-:RT ET AL 3,391,641

OUTPUT REGULATED PUMP Filed M ay 1l. 1966 United States Patent O3,391,641 OUTPUT REGULATED PUMP Konrad Eckert, Stuttgart-Bad Cannstatt,Gerald Hofer, Stuttgart, and Claus Koster, Unterweissach, Germany,assignors to Robert Bosch G.m.b.H., Stuttgart, Germany Filed May 11,1966, Ser. No. 549,227 Claims priority, application France, May 14, 19651o ciaims.(c1. nis-2) ABSTRACT F THE DISCLDSURE A throttle is providedin a supply conduit for connecting an auxiliary pump with the cylinderof a control valve controlling the relief conduit of a fuel pump so thataxial oscillations of the control valve are .dampened and the regulationof the output of the main pump is improved since the movement of thecontrol valve is delayed and the relief conduit is later opened ascompared with an arrangement without the throttle.

The present invention relates to an output regulated pump, and moreparticularly to a fuel injection pump whose output is regulated so thatthe amount of fuel injected into a combustion motor docs not rise inproportion to the increased speed of the combustion motor.

Fuel injection pumps are known whose output is regulated in accordancewith the liquid stop principle. In pumps of this type, a control pistonis provided in a control cylinder for relieving at the proper moment thepressure of the fuel injection pump. The control piston is moved by fuelflowing through a supply conduit to a. relieving position, and is biasedto return while pressing the fuel through a throttling conduit.

In fuel injection pumps of this type, the mass of the control piston,and the fuel in the regulating conduits, forms an oscillatable systemwhich is excited by the mass `forces at each stroke of the controlpiston. The axial oscillations of the control piston disturb theaccurate regulation and inuence the regulation of the amounts of fuelpumped by the injection pump.

lt is one object of the invention to improve regulated pumps,particularly fuel injection pumps, and to provide a reliably operatingoutput regulated pump.

Another object of the invention, is to dampen oscillations of a iluidmedium in the control conduit means of the pump.

Another object of the invention is to provide a pump whose output isautomatically regulated.

Another object of the invention is to delay the relief action of thecontrol piston so that the output of the injection pump at high speedsis influenced.

With these objects in View, the present invention re lates to an outputregulated pump, comprising a main pump, an auxiliary pump operating insynchronism with the main pump, and control valve means including acylinder located in a relief conduit of the main pump and having anoutput conduit, and a reciprocable valve mem ber biassed to move in onedirection for closing the output and relief conduits.

Supply conduit means and throttling return conduit means connect theauxiliary pump with the control cylinder so that the auxiliary pumppumps a fluid, preferebly fuel, through the supply conduit into thecylinder for moving the valve member to open the relief conduit and toconnect the supply conduit with the outlet conduit. The supply conduithas a check valve blocking flow into the auxiliary pump so that thefluid flows through the throttling return conduit into the auxiliarypump while the biassed valve member moving in one direction urges thefluid out of the cylinder. This results in shorter strokes 3,391,641Patented July 9, 1968 ICC of the valve member at high speeds of thepumps so that the output of the main pump is reduced. In accordance withthe invention, throttle means are provided in the supply conduit fordelaying the movement of the valve member to the position in which thepressure of the main pump is relieved and its injection stroketerminated. Furthermore, oscillations in the supply conduit aresuppressed and dampened.

In order to prevent that an unduly great part of the fluid flows throughthe throttling return conduit, the throttle means in the supply conduithas a greater open cross-section than the throttling conduit, and if thethrottling conduit is provided with an adjustable throttle, thethrottling means in the supply conduit has a greater open cross-sectionthan the maximum cross-section of the adjustable throttle in the returnconduit.

The supply conduit is provided `with a check valve which blocks flowfrom the control cylinder back into the auxiliary pump. In the preferredembodiment of the invention, the throttling means is disposed in thesupply conduits between the control cylinder and the check valve so thatthe fluid pumped by the auxiliary pump first passes through the checkvalve and then through the throttle means.

The novel features which are considered as characteristie for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of a specificembodiment when read in connection with the single iigure of theaccompanying drawing which is a schematic sectional view of an injectionpump according to the invention.

Referring now to the drawing, a main pump has a piston .l mounted in acylinder 2 for reciprocating axial movement, and for turning movementabout its axis. During the turning movement, piston 1 acts as adistributor by supplying during its pressure stroke, amounts of fuelsuccessively to a series of delivery conduits 3 which are angularlyspaced equal distances around cylinder 2. The number of deliveryconduits 3 is the same as the number of cylinders of a combustion engineinto which fuel is injected by the main pump 1, 2. A check valve 4 isdisposed in each of the delivery conduits 3.

The cylindrical surface of piston 1 has a groove 5 which connects thecylinder chamber 6 successively with one of the delivery conduits 3 whenpiston 2 is angularly displaced during cach stroke. Consequently, duringsuccessively pressure strokes of piston 2 into chamber 6, differentdelivery conduits 3 receive fuel which is sucked into cylinder 6 throughan inlet 1U communicating with a suction chamber il filled with liquidfuel. Chamber 6 communicates with inlet it) through a duct 7, an annularchamber S and angularly spaced grooves 9, a different groove 9communicating with inlet 1t) during successive suction strokes andangular displacements of main piston 1. A pump, not shown, lpumps fuelfrom a tank into the chamber 11. During the suction stroke of mainpiston 1, fuel flows from suction chamber 11, and passages 10, 9, 8, 7into chamber 6, and during the pressure stroke, fuel is dischargedthrough groove 5 and a delivery conduit 3 and check valve 4 into thecylinder of a combustion engine, not shown.

A relief conduit 13a, 13b connects cylinder chamber 6 with suctionchamber 11, and includes a cylinder portion 22a of a control cylinder 22located between two portions 12a, 12b of a control valve member 12 whichhas a reduced portion 12e located in cylinder portion 22a. A spring 14abuts a flange 15 of control valve member 12 and urges the same to aposition in which liangc i5 abuts a surface 16 of the supporting body ofthe apparatus. ln this normal position of control valve means 22, 12,relief conduit 13a, 13b is closed by valve portion 12b so that a certainamount of fuel is discharged during each pressure stroke of main piston1 through the respective delivery conduit 3.

An auxiliary pump including a cylinder 18 and a piston 17 operates insynchronism with the main pump, since pistons 1 and 17 are connected. Arotary cam, not shown, acts on piston 17 to obtain synchronousreciprocation of pistons 17 and 1. The chamber formed in cylinder 18 bypiston 17 communicates through axial, angularly spaced grooves 19 withan inlet 25 communicating with the suction chamber 11 so that theauxiliary pump 17, 18 pumps a liquid fuel. However, the auxiliary pumpcould also be operated with another liquid.

A supply conduit 20 connects auxiliary pump 17, 18 with a chamber incontrol cylinder 22 located on the left of piston portion 12a. A checkvalve 21 is located in supply conduit 20, blocking tiow from controlcylinder 22 into cylinder 18 through one of the grooves 19, butpermitting flow of iluid pumped by piston 17 into control cylinder 22. Areturn conduit 27 connects supply conduit 20 and control cylinder 22with cylinder 18 of the auxiliary pump.

When piston 17 is reciprocated together with main piston 1, the fuel ispumped through supply conduit 20 into control cylinder 22 and movescontrol valve member 12 against the action of spring 14 to a position inwhich cylinder portion 22a connects relief conduit portions 13a and 13bso that the pressure in cylinder chamber 6 of the main pump is relieved,and delivery of fuel through the respective delivery conduit 3 to thecombustion engine is terminated.

When auxiliary piston 17 moves downward in a suction stroke, inlet 2Scommunicates through one of the grooves 19 with cylinder 18 when piston17 arrives at its lower dead center position, or already during thedownward stroke.

The supporting body of the device has a bore in which a throttle member28 is mounted for turning movement. Throttling member 28 has threeportions 28a, 28b, and 28C, portion 28e separating two chambers.Portions 28a and 28h have slanted surfaces cooperating at throttlingpoints 24 and 26 with an outlet conduit 23 and a return conduit 27.

During the upward pressure stroke of pistons 17 and 1, fuel isdischarged through delivery conduit 3, and is also pumped through supplyconduit it) into cylinder 22 so that cylinder chamber 6 is relieved whenpiston portion 12b of control valve member 12 opens relief conduitportion 13b so that the same can communicate through cylinder portion22a with relief conduit portion 13a. While control valve member 12 movesfurther to the right against the action of spring 14, piston portion 12uassumes a position establishing communication between outlet conduit 23and cylinder chamber 22 so that the pressure is relieved, and the forceof spring 14 is sutiicient to return control valve member 12 toward theleft as viewed in the drawing. As soon as outlet conduit 23 is againclosed by piston portion 12a, discharge through outlet conduit 23 is nolonger possible, and the fuel in cylinder chamber 22 is pressed by theaction of spring 1li through throttling return conduit 27 overthrottling point 26 into cylinder 18 of the auxiliary pump.Consequently, the movement of control valve member 12 toward the left asviewed in the drawing is braked and slowed down to an extent dependingon the adjustment of the throttle point 26 by turning adjustment ofthrottling member 28.

When the speed of reciprocation of pistons 17 and 1 reaches apredetermined high speed, the so-called liquid stop effect takes place,and control valve member 12 cannot return to its left dead-centerposition before new fuel is pumped by auxiliary piston 17 through supplyconduit 20 into cylinder chamber 22. Consequently, the length of thestroke of valve member 12 is shortened, and relief conduit portions 13a,13b will be sooner connected to each other during the pressure stroke ofauxiliary piston 17. As a result, a smaller amount of fuel is deliveredthrough the respective delivery conduit 3 during each pressure stroke ofmain piston 1, since cylinder chamber 6 is relieved before the end of afull stroke of main piston 1.

In accordance with the present invention, a throttle means 29 is alsoprovided in the supply conduit 26, and as shown in the drawing,downstream of the tlow of lluid from cylinder 18 into control cylinder22. In other words, throttle means 20 is located between the check valve21 and cylinder 22 in the preferred embodiment of the invention.

Throttle means 29 dampens axial oscillations of control valve member 12,reduces the amplitude of such oscillations, and consequently improvesthe stability of the regulation of the output of main pump 1.

Throttle means 29, which may also be made adjustable, produces apressure drop which rises at increasing Speeds so that, depending on thespeed of operation of the auxiliary and main pumps, the start of themovement of control valve member 12 toward the right is delayed. Due tothis delay of the movement of control valve member 12, and a consequentlater opening of the relief conduit 13a, 13b, the amount of fueldelivered to the injection nozzles of the combustion engine throughdelivery conduit 3 is increased.

The volumes of uid between auxiliary piston 17 and throttle means 29 onone hand, and between throttle means 29 and valve member 12 on the otherhand, can be selected so that the ratio between these volumes causes apredetermined delay of the start of control valve member 12 toward itsrelieving position whereby at increasing driving speed, the amount offuel delivered through delivery conduit 3 to the injection nozzles ofthe combustion engine rises to a desired extent. Consequently, throttlemeans 29 permits an adjustment in regulation of the amount of deliveredfuel depending on the number of revolutions of the combustion engine,and of the drive cam means reciprocating pistons 17 and 1.

Different types of throttle means 29 may be used. Supply conduit meansmay be simply provided with a constricted portion, or a diaphragm withan opening may be inserted into supply conduit 20, or a stop may beprovided for limiting the movement of the ball of check valve 21 so thatthe same forms a throttle means in the supply conduit 20 effectiveduring pumping of fuel from cylinder 18 into control cylinder 22.

In the illustrated embodiment which provides an adjustable throttle 26,28a in the return conduit 27, it is necessary that the open freecross-section of throttle means 29 is greater than the maximum openingof throttle 26. A greater part of the iluid which operates control valvemember 12, must flow through supply conduit 20 then through returnconduit 27.

In an actual embodiment of the invention, throttle means 29 has a freeopen cross-section of 0.78 mm2, while the free open cross-section ofthrottle 26 is adjustable between 9.03 mm2 and 0.46 mm2.

It Iwill be understood that each of the elements described above, or twoor mo-re together, may also tind a useful application in other types ofinjection pumps differing from the types described above.

While the invention has been illustrated and described as embodied in anoutlet regulated pump including a throttle means for delaying the reliefof the pressure of a yfuel injection pump, it is not intended to belimited to the details shown, since various modifications and structuralchanges may be -made without departing in any way from the spirit of thepresent invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specic aspects of this invention and,therefore, such adaptations should and are intended to be comprehendedlwithin the meaning and range of aquivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. Output regulated pump comprising, in combination, main pump meanshaving an inlet, at least one delivery conduit, and a relief conduit,control valve means including a control cylinder member located in saidrelief conduit and having an outlet conduit and a throttling returnconduit, and a reciprocable control Valve member located in saidcylinder member, one of said members being biassed to move in onedirection to a position closing said outlet and relief conduits;auxiliary `pump means operating in synchronism with said main pump meansand having an inlet for a duid; and supply conduit means connecting saidauxiliary pump means Vwith s-aid cylinder member so that said auxiliarypump means pumps the Huid through said supply conduit means into saidcylinder member for moving said biassed member opposite to said onedirection for first opening said relief conduit and then connecting saidsupply conduit means 4with said outlet conduit so that when flow of Huidthrough said supply conduit means into said auxiliary pump means isblocked, the tiuid is pressed through said throttling return conduitmeans by said biassed member returning in said one direction whereby athigh speeds of said pump means said biassed member moves shorter strokesso that the output of said main pump means is reduced; and throttlemeans in said supply conduit means for delaying the movement of saidbiassed member in said opposite direction and thereby the opening ofsaid relief conduit.

2. A pump according to claim 1 and including an adjustable throttlemeans in said throttling return conduit means.

3. A pump according to claim 1 and including an adinstable throttlemeans in said throttling return conduit means; and wherein the opencross-section of said throttle means in said supply conduit means isgreater than the maximum open cross-section of said throttle means insaid return conduit means.

4. A pump according to claim 1 comprising a check valve in said supplyconduit means for blocking flow into said auxiliary pump means; andwherein said throttle means in said supply conduit means is locatedbetween said cylinder and said check valve.

5. A pump according to claim 4 ywherein said throttling return conduitmeans has a smaller open cross section than said throttle means in saidsupply conduit means and 5 -is connected ywith said auxiliary pumpmeans,

6. A pump according to claim 1 including means for supplying a liquidfuel to said in-lets of said main pump means and of said auxiliary pumpmeans; wherein said main pump means includes a main piston mounted foraxial -re-ciprocation and for angular movement; and including aplurality of delivery conduits, said main piston having an Vaxial groovesuccessively communicating with said delivery conduits during angularmovement of said main piston.

7. A pump according to claim 1 including a manually operated throttlingmember located in said outlet and return conduits, and being operablefor adjusting the free cross-section of said outlet and return conduits.

8. A pump according to claim 4 wherein said throttle means is locatedadjacent said check valve between said check valve and said controlcylinder, and wherein said check valve is located adjacent saidauxiliary pump means.

9. A pump according to claim 1 wherein said control valve member forms achamber in said control cylinder located on one side of said controlvalve member; and wherein said supply and return conduit meanscommunicate with said chamber.

10. A -pump according to claim 9 wherein said control valve member hastwo piston end portions, and a reduced portion between said piston endportions, said reduced portion and piston end portions forming anannular chamber; -wherein said relief conduit has a first relief conduitportion communicating with said delivery conduit of said main pumpmeans, and an other relief conduit portion, one of said relief conduitportions being normally closed by one of said piston end portions, andsaid annular cylinder chamber connecting said relief conduit portionswhen said control valve member is moved in said opposite direction outof its normal position.

References Cited UNITED STATES PATENTS 2,950,709 8/1960 Bessiere 103--41X 3,011,489 12/1961 Bessiere 103-41 X 3,044,404 7/1962 Bessiere 103--413,090,314 5/1963 Bessiere 103-41 3,114,321 12/1963 Bessiere 103--413,122,100 2/1964 Bessiere 103-42 X 3,267,865 8/ 1966 Deininger 103--42FRED C. MATTERN, IR., Primary Examiner.

-DONLEY J. STOCKING, Examiner.

W. I. KRAUSS, Assistant Examiner.

